This application claims the priority of German patent documents 102 41 133.6, filed Sep. 3, 2002 and 103 32 502.6, filed Jul. 17, 2003 (PCT International Application No. PCT/EP2003/009332, filed Aug. 22, 2003), the disclosures of which are expressly incorporated by reference herein.
The invention relates to a radio-based device for issuing hazard warnings to the operator of a vehicle.
European patent document EP 927 983 A2 discloses a radio based hazard warnings device, in which, in a vehicle that receives a hazard warning, the difference between the speed of a transmitting vehicle and the receiving vehicle is determined, and on the basis of the determined difference in speed a decision is made as to whether a warning signal is output to the driver.
French patent document FR 2 793 056 discloses a device for issuing hazard warnings, in which the type of hazard is indicated in the vehicle. In the receiving vehicle it is determined whether it is necessary to output the warning to other vehicles.
International patent document WO 01/61668 A1 discloses a hazard warning device, in which a warning zone is generated in the transmitting vehicle and is output together with the hazard warning. In the transmitting vehicle, the position of the vehicle and the type of road on which the vehicle is located are determined using a navigation system. The difference between the speed of the transmitting vehicle and the typical or maximum speed of other vehicles on the given type of road is included in the calculation of the warning zone in the transmitting vehicle. The received hazard warning is evaluated in the receiving vehicle using a navigation system, by checking whether the receiving vehicle is in the warning zone and whether the hazard warning relates to a section of road which possibly lies in front of the receiving vehicle.
In the publication “WARN—ein neues funkbasiertes Gefahrenwarnsystem im Kfz für mehr Sicherheit im Straβenverkehr [WARN—a new radio-based hazard warning system in motor vehicles for providing more safety in road traffic]”, Brenzel, C., Hickel, F., Paβmann, C., VDI Berichte [VDI Reports] No. 1415, 1998, the type of hazard, the speed of the transmitting vehicle and information about the position of the transmitting vehicle are to be transmitted, together with the hazard warning. In the receiving vehicle, the difference in speed relative to the transmitting vehicle is determined, and information about the position of vehicles is used to determine whether the warning message has been generated by a vehicle traveling in front, by a vehicle traveling behind, or by the oncoming traffic.
In the document “Wireless Vehicle to Vehicle Warning System”, Paβmann, C., Brenzel, C., Meschenmoser R., SAE Paper, 2000-01-1307, icons which symbolize the type of hazard are displayed in the receiving vehicle. In addition, the distance from the location of the hazard is indicated in the receiving vehicle.
German patent document DE 199 52 392 A1 discloses a method in which warning information that is dependent on the route is made available to the driver. Digital road maps are used to detect, for example, whether the driver is approaching a curve. If so, and if the current speed of the vehicle is higher than a speed limit for the curve, the driver is first warned visually. If he or she does not react to the visual warning within a certain time (i.e., if he or she continues to drive with undiminished speed), an additional audible warning is issued. Since the curve has a fixed position, the approach to it is always detected at a sufficiently large distance ahead, and various warning stages of increasing urgency are successively triggered.
One object of the invention is to provide an improved method and apparatus for issuing hazard warnings, including an improved manner of outputting information to the driver.
This and other objects and advantages are achieved by the radio based hazard warning device which generates a hazard warning that extends beyond the visual range of a hazard warning system, thereby extending the range of the classic hazard warning system. A significant component of the device is a radio modem which permits direct exchange of data between vehicles in real time, with a sufficiently large range of approximately 1 km. In addition, the device may also include a locating module with which the position of the vehicle can be determined by locating means. The locating module may be a component of (or connection to) a navigation system, so that the position of the vehicle can be determined with even greater accuracy because the measured position of the vehicle can be represented on the digital map of the navigation system by map matching. As a result, errors in the determination of a position can be compensated by the locating module.
The data which are received by the transmitting vehicle include information regarding the position of the transmitting vehicle, determined by a locating device and/or a directional course of the vehicle. A directional course of the vehicle is formed from the direction of travel and speed of the vehicle at various times. The received information relating to the position may also include additional information about earlier positions of the transmitting vehicle, forming a position chain of the vehicle which is composed of a sequence of points at which information relating to the position of the vehicle is present. In this context the position chain can be a directional course and/or a sequence of positions which are determined by means of a locating system or navigation system.
In one advantageous embodiment of the invention, a relevance measure is determined from the received data of the transmitting vehicle and the position, speed and direction of travel data of the receiving vehicle. The relevance measure expresses the probability that the transmitting vehicle is located on the part of a route lying in front (that is, upstream) of the receiver. The receiving vehicle advantageously has information about the route which is used to estimate in advance its future route. The relevance measure (which expresses the probability that the transmitting vehicle is located on the predicted future route of the receiving vehicle) is advantageously determined from the received data of the transmitting vehicle and the predicted future route of the receiving vehicle.
In another advantageous embodiment of the invention, incorrect warnings are detected by reference to a time profile of the relevance measure. This means, for example, that information whose relevance measure is too low is not output.
In still another advantageous embodiment of the invention, the outputting of information to the driver is terminated as soon as a warning is determined to be incorrect. In this context, it is advantageous if, as soon as the outputting of information is terminated due to an incorrect warning, the driver is explicitly informed, by means of a directly following information output, that the previously reported hazard is no longer relevant to him.
The decision as to whether information is output to the driver is taken during the evaluation of a received radio message in a computer unit in the receiving vehicle. The basic idea of the triggering concept is that the decision as to whether information is output to the driver includes at least the approach speed between the transmitting and receiving vehicle and the distance between the two vehicles. As a result, the invention allows for the fact that for the urgency level of a warning, it is particularly decisive how much time remains for the driver to react to the warning and brake his vehicle. This time is however calculated at least from the distance and the relative speed between the receiver and transmitter so that both variables are decisive for the triggering concept (that is, the decision as to when information is output and the decision as to when the outputting is terminated).
By linking the distance to the approach speed, the time which remains until the transmitter is reached becomes the determining variable for triggering. This also corresponds to the human perception of hazards in road traffic. The driver evaluates the degree of danger of a situation mainly according to the time which remains to carry out necessary actions and driving maneuvers in order to avoid an accident.
A warning is not triggered if the distance from the transmitter is so long or the approach speed so low that there is initially no need for action on the part of the driver. Likewise, the triggering can, if desired, be adapted in such a way that triggering of a warning is dispensed with if the distance is so short or the approach speed so high that the driver would no longer be able to react appropriately to the warning before reaching the transmitter as a result of the short prewarning time.
In an embodiment of the invention, an urgency level for outputting information is determined using the distance between the transmitting vehicle and receiving vehicle, as well as the approach speed of the transmitting vehicle and receiving vehicles.
In another advantageous embodiment of the invention, the manner of outputting information to the driver depends on the determined urgency level, based on the distance and the relative speed between the receiver and transmitter.
How and when the driver is informed about a received radio message depends on the urgency level. This is advantageous in particular for the high speeds at which vehicles travel on highways, at which the driver must concentrate entirely on the task of driving and is capable only to a limited degree of absorbing information and warnings which are output by a vehicle system. The driver can intuitively understand the warnings and react to them correctly.
The invention helps to prevent, for example, mass vehicle pileups which can occur on motorways, frequently due to poor visibility conditions (for example fog), on sections of a route with poor visibility (for example before a curve which cannot be seen into satisfactorily) or traffic disruption (for example the end of congestion or roadworks). The radio based hazard warning device according to the invention makes it possible for the drivers of following vehicles to detect the hazard ahead in sufficient time to be able to brake their vehicle and avoid the hazard. In one embodiment of the invention, the vehicle can be braked automatically by an intervention in vehicle control systems.
In addition to the distance and the approach speed of the receiver and transmitter, a further embodiment of the invention takes into account additional data in order to decide to trigger a warning, as well as its urgency level. Examples of such data are the speed and acceleration of the receiving vehicle and the time which has passed since the last warning. Information about routes (determined, for example, by means of a digital roadmap) can also be used to determine the urgency level.
It is thus advantageous to trigger a warning only if the receiver is driving sufficiently fast, since at low speeds timely visual detection of the hazard by the driver is ensured, and an additional warning by the system is thus unnecessary.
By reference to the current acceleration of the vehicle, it is possible to check whether the driver of the receiver is already braking hard enough to avoid a rear end collision with the transmitter. If so, a warning can also be dispensed with.
Finally, the urgency of a warning can also be defined as a function of the time which has passed since the last warning. If two warnings follow one another in rapid succession, it is reasonable to assume that the driver is still traveling with increased alertness due to the first warning. For this reason, a low urgency level can also be assigned to the second warning if the transmitter will be reached within a short time.
In an advantageous embodiment of the invention, the radio based hazard warning device comprises a data transmitter which is triggered, for example, by the hazard warning system of the vehicle. If the hazard warning system is triggered, a corresponding radio message is emitted to all the vehicles in the vicinity of the transmitting vehicle. The transmitted data of each transmitter includes its current speed, its position chain and a type of hazard. In one embodiment of the invention it is also possible for the transmitter to transmit its identification number.
In another advantageous embodiment, information about the degree of urgency is output by a voice output means, and/or by means of a single time voice output.
Using an indicating/display method, one of a plurality of predefined indicating display modes, which includes at least a voice output and a further type of indication, are selected as a function of the urgency.
Issuing different voice outputs in order to distinguish between different urgency levels combined with an additional type of indication (for example, a visual display and/or a haptic indication) has the advantage that the corresponding voice output already contains the important information without requiring that the driver interrogate a further information source for this purpose (for example, without the driver's having to read a display unit for presenting a visual display). The additional visual display serves only as a visual information store which the driver can access when necessary in order to refresh the information. As a result, distraction is minimized and the comprehensibility of the warnings and the acceptance of the system are increased.
According to an advantageous embodiment of the invention, the voice output for a first urgency level, which is determined with a low degree of urgency, can contain information which indicates the approximate distance from the source of the hazard. Such information informs the driver that he still has sufficient time to reduce his or her speed by releasing the accelerator and possibly braking slightly.
When a second urgency level with a high degree of urgency is determined, a warning indication can be output which signals to the driver that a rapid reaction is necessary, and that he or she must implement a braking deceleration process which may lie outside the normal range of driving comfort.
At both urgency levels, the voice output is carried out for the purpose of keeping the distracting effect as low as possible. The different degrees of urgency are conveyed by the various contents and formulations of the voice output.
In an alternative embodiment of the invention, at least one of the indicating display modes can comprise a single time voice output which warns of the hazard and contains information about the degree of urgency which has been determined. The distraction of the driver is reduced further by the fact that the voice output occurs only once.
In addition to information about the degree of urgency of the hazard warning it is also possible, for example, to use a visual display and/or the voice output to indicate information about a type of hazard for the two urgency levels.
In order to determine the urgency, for example external data are received from other vehicles or from a control center and evaluated. Alternatively or additionally it is also possible to evaluate data from vehicle sensors which can also comprise a locating system with a digital map and/or a navigation system.
In order to carry out the indicating/display method, the indicating/display device according to the invention comprises a control/evaluation unit, a voice output unit with a specific functionality and a further indicating/display unit.
In addition, it is possible to provide a data receiver and/or a sensor unit at the vehicle end which, for example, provide the control/evaluation unit with data for determining the urgency and/or the distance from the location of the hazard. External data, for example from other vehicles or from a control center, can also be evaluated by the data receiver.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.